These airports were converted to Orbiter by my xp2o program, using Robin Peel's publicly-available data.

London City - not the most obvious choice for a London spaceport, but anything that goes wrong will fall on Essex or France.	Diego Garcia - a hellish posting in the Indian Ocean, but only seven degrees south of the equator, no neighbours to complain, and it already has a massive runway.
Paris Charles de Gaulle	Amsterdam Schiphol
Albuquerque International Sunport (see details at airnav.com)	Las Vegas McCarran International (see details at airnav.com)
John F Kennedy Intl (see details at airnav.com)	Los Angeles Intl (see details at airnav.com)
Seattle Tacoma Intl (see details at airnav.com)	Meigs Field - it's the principle of the thing!
Galeao Antonio Carlos Jobim - Rio de Janeiro's main airport, somewhat underused these days but good for eastward over-water launches.	Guarulhos - Brazil's main international airport, near Sao Paolo. (Don't ask me about the coloured lights! Must be Carnival time.)
Quito Mariscal Sucre Intl - nearly equatorial and handy for the Americas
Cape Town International - good for southern launches to polar orbit	Johannesburg International
Moscow Sheremetyevo
Sydney Kingsford Smith Intl